For a plastering, as a rule, use sculptural clay, air izvest, plaster.
Clay - a material received from rocks, inclined to aeration. It is one of the most suitable for a moulding of materials thanks to the specific properties: plasticity and ability to keep the form. Clay gets plasticity at mixing with a certain quantity of water then it can accept the demanded form which keeps as a result of roasting or drying. Thus the product loses in volume that is called usadkoj a little. .
Clay Kinds differ on structure. The most suitable to a moulding clay in which few impurity and sand - so-called fat clay contain is considered. It is most plastic and in the course of work does not stick to hands. For reception of fat clay it is possible to use lean (containing many impurity), having removed from it sand.
The Basic inconvenience at work with clay is that it quickly dries up. That it has not occurred, it is necessary to add on 1 kg of clay of drying oil of 0,5 kg or 0,2 kg kastorovogo oils.
If process of manufacturing of a stucco moulding lasts long enough the prepared clay is better to store, having covered with a wet fabric. Only in this case it keeps plasticity and remains suitable to the use during necessary term before work end. .
Air izvest receive as follows: at first the chalk or limestone heat up to 1000-1200 °s, and then received oksid calcium extinguish, i.e. Water. The dough which volume in comparison with initial increases several times turns out. It plant with water and use further as the additive to plaster.
For reception of a qualitative material for a moulding the plaster stone, passes high-temperature processing and is pounded in a powder. .
At manufacturing of decorative details of a facade the fresh plaster which is not containing sand is used. Mixed with water, it quickly hardens that can affect productivity of work. Usually plaster stiffens during 6 - 30 minutes, but by means of various impurity process of hardening of this material can be accelerated or slowed down. The stiffening plaster repeatedly dissolved with water, it is impossible to use. .
Finished articles at hardening slightly increase in sizes, therefore plaster is the most convenient material at work with small forms with which it is capable to fill very densely.
For preparation of a plaster solution the crushed plaster scatter on a water surface and wait, while it will settle. Then a solution stir a shovel before reception smetanoobraznoj weights. It is necessary to observe precisely the set proportions as at powder addition in ready weight in it lumps are formed. To receive a dense solution, in 1 l of water plant 2 kg of plaster. If the liquid or normal solution is required, besides to a quantity of water add 1 and 1,5 kg of a plaster powder accordingly. .
That plaster ornaments have for a long time kept the form, them dry at temperature not above 70 °s, differently they will lose durability. The finished article should be stored in a dry place as at contacts to water plaster is softened.